This nozzle is "optional", its 0.3mm size (compared to the 0.4mm supplied "standard" in the Caravaggio kit) will allow you to create finishes and shades of absolute precision.; its particular threadless design makes it a strong point as disassembly and cleaning are very quick and easy to do every time.
NOTE: with this nozzle it is also necessary to combine its specific needle #AX180-01503 and also its nozzle cap #AX180-00203